Question

if \\(\frac{7}{x} = \frac{21}{12}\\), what is the value of x ?

Explanation:

Step1: Cross - multiply the proportion

Given the equation \(\frac{7}{x}=\frac{21}{12}\), by cross - multiplying (which is based on the property of proportions: if \(\frac{a}{b}=\frac{c}{d}\), then \(a\times d = b\times c\)), we get \(7\times12=21\times x\).

Step2: Simplify the equation

Calculate \(7\times12 = 84\) and \(21\times x=21x\), so the equation becomes \(84 = 21x\).

Step3: Solve for x

Divide both sides of the equation \(84 = 21x\) by 21. \(\frac{84}{21}=x\), and \(\frac{84}{21} = 4\).

Answer:

4 (and the option corresponding to 4, e.g., if the fourth option is "4", then the answer is the option with 4, say D. 4)